Something like this?
Looks like they made a a few different configs. I found this link over on the H.A.M.B. and will cut and paste one fellows comments here"
"...I've delved into this a whole lot. I have in my shop a C3B, C4B and C3BX. The intake runner layout is different on my C4B than the other two. It has a pair of real short runners, and a pair of real long runners. The carb base is a 4-hole base.
The C3B and C3Bx have a divided 2-opening plenum, with the notch for the Holley 3BBL carb in the plenum divider. The high and low side of the plenum floors is opposite the C4B, and the runners are more equal in length. It's clear this is the version the Performer was patterned after.
HOWEVER, I've also seen pics of a C3B WITHOUT the notch for the plenum, and I've seen pics of a C4B with a divided plenum and evenly spaced runners.
In short, I've seen every combination of plenum/carb pad with each designation.
AND, I've seen all of them with the fill tube going out the right, or going out the left, with the T-stat housing going the opposite way.
On the C3B I've got, and the C3BX, the only difference I see is a couple of different ports up front for the heater hoses (drilled/tapped versus the boss is there but not drilled), but more importantly, my C3BX has the boss for a choke mechanism cast into it. My C3B and C4B do not have those, and I haven't seen any of the others since to compare."
Here is the link for those who want to poke around.
http://www.jalopyjournal.com/forum/s...d.php?t=375152